The long term goal of this proposal is to understand the molecular mechanisms that influence the formation and maintenance of neuronal synapses. These processes are vital to nervous system function, and diseases that disrupt such mechanisms may lead to neurodevelopmental and neurodegenerative diseases. The Drosophila neuromuscular junction is an important model system for the molecular characterization of these mechanisms. In a screen of Drosophila mutants, we have recently identified a previously uncharacterized Drosophila gene (CG17667) that influences the normally tight apposition of the presynaptic active zone with postsynaptic glutamate receptor clusters. In this proposal, we plan to investigate the role that this gene plays in active zone formation and maintenance by 1) characterizing the mutant phenotype and 2) determining the localization and spatial, temporal, and structural requirement of the protein encoded by the gene. In addition, we will 3) continue the screen that originally identified this gene to identify additional molecules involved in synapse formation and maintenance. [unreadable] [unreadable] [unreadable]